AIMTo investigate the effects of RLI on plasma nitric oxide (NO) and NO synthase (NOS) isoforms of healthy humans.

METHODS30 healthy human subjects (aged from 40 - 70 years old) were recruited. RLI was induced by five 5 min cycles of ischemia of non dominant arm (200 mmHg, 5 min interval). Blood pressure, heart rate, and the feelings of ischemic arm were continuously monitored. Venous plasma was collected in contralateral arm at Pre, Post-0 h, Post-4 h, and Post-24 h. Plasma level of NO was measured by Griess reaction, and NOS was measured by chemical method.

RESULTSBlood pressure and heart rate varied in normal range. The uncomfortable feeling was decreased with the increasing numbers of ischemic cycles. Plasma level of NO, and iNOS in plasma were significantly increased at Post-0 h, Post-4 h, and Post-24 h compared to Pre (P < 0.05). tNOS was also significantly increased at Post-0 h and Post-4 h compared to Pre (P < 0.05). No significant change in plasma cNOS was shown at following three time points than Pre.

CONCLUSIONThese findings suggest that RLI can elevate plasma level of NO, tNOS, and iNOS in healthy humans. RLI might be a safe method as a rIPC, and it would have important possibility to be performed in clinic.